Risso's dolphin calf found on Heckscher State Park beach in East Islip

A member of a species of dolphin usually found in mid-temperate, deeper waters was among a pair of dolphins discovered on South Shore beaches in Suffolk this weekend, according to the Atlantic Marine Conservation Society.

The Hampton Bays-based organization said a male Risso’s dolphin calf was found at Heckscher State Park in East Islip on Friday and a bottlenose dolphin was discovered east of Sore Thumb Beach in Babylon on Sunday.

“It was emaciated and doesn’t appear to have been eating,” Atlantic Marine Conservation Society executive director Robert DiGiovanni said of the Risso’s dolphin calf, an unusual find for the area. “It looks like it was a dependent calf.”

DiGiovanni said the calf had been observed swimming in waters around Heckscher State Park for about 48 hours before it was called in dead. He said that while it is not completely uncommon to find a Risso’s dolphin in New York waters, they are not typically found inshore.

“The interesting thing about Risso’s to begin with is that they are usually considered more of an offshore species,” DiGiovanni said. “They're usually up on the shelf break.”

While Risso’s dolphins, which can dive to depths of more than 1,000 feet, are spotted in small numbers in local waters, DiGiovanni said there has been a moderate increase in sightings in recent years. He said it is difficult to say exactly why the dolphin may have come in closer to shore because it didn’t appear to be in pursuit of food. This weekend’s stormy conditions may have been a factor, but it “can be problematic to speculate,” DiGiovanni said.

The bottlenose dolphin discovery in Babylon is less rare, but still an unusual find, he added.

At least 17 whales have washed up near the New York-New Jersey region this year, marking a record number of dead whales in the region.

A recent study found that warming ocean temperatures, rising sea levels and decreasing sea ice volumes associated with climate change, are major threats to American marine mammal species such as whales, dolphins and seals. National Oceanic and Atmospheric Administration researchers examined more than 100 stocks of marine mammal species and found more than 70% are vulnerable to loss of habitat and food, because of warming waters. 

Other threats to Risso’s dolphins include entanglements related to commercial fishing, contaminants, underwater noise and hunting in other regions of the world.

Risso’s dolphins usually prefer deeper offshore waters, where they can dive to at least 1,000 feet and hold their breath for 30 minutes, according to the National Oceanic and Atmospheric Administration Fisheries. The mammals are usually medium-sized and can reach lengths of about 8½ to 13 feet and weigh between 660 to 1,100 pounds. Risso’s dolphins have an estimated life span of at least 35 years.

The team sent to Heckscher was able to determine that the dolphin found was young because of its size, about 6½ feet long, and because it was darker with less scarring to its body. The bottlenose dolphin was also a male, just under nine feet, DiGiovanni said.

The conservation society asks that anyone who spots a Risso’s dolphin, or any other unusual marine animal, contact them at sightings@amseas.org or by calling the hotline at 631-369-9829.

“This is an opportunity for people to really help us,” DiGiovanni said. “From an observational standpoint, somebody else might have seen this animal before this happened. Reporting sightings … is really a critical factor in trying to understand what’s changing.”